1. Field of the Invention
The present invention relates to a driving device, a flasher device and a projector.
2. Description of Related Art
A switching regulator is a circuit to convert direct-current input voltage into direct-current output voltage by turning a switching element on and off. Such a switching regulator is used for an electrical power supply or a driver for various loads (see Japanese Patent Application Laid-Open No. 2010-110190, for example). The controller of the switching regulator performs PWM (pulse width modulation) control over a switching element by outputting a PWM signal to the switching element. The controller feeds back inductor current of the switching regulator and monitors the fed-back current to generate a PWM signal having a duty cycle based on the fed-back current. In this way, constant current control is performed where the inductor current is maintained constant. Examples of such current mode control include average current mode control (see Japanese Patent Application Laid-Open No. 2010-110190, for example). The average current mode control is a control system to maintain the average value of inductor current constant by monitoring the average current value of inductor current including a ripple and by generating a PWM signal having a duty cycle based on the average current value.
Right after the controller of the switching regulator starts to operate, the output voltage of the switching regulator goes into a steady state later than inductor current when the average value of the inductor current moves from a transient state to a steady state due to the effect of a smoothing circuit of the switching regulator or the like. This also causes the output current of the switching regulator to go into the steady state later than the inductor current. When the controller repeatedly operates and stops operating so as to enable and disable a load repeatedly, the output current of the switching regulator goes into the steady state late every time the controller comes into operation. This prevents the increase in speed of enabling/disabling of the load.